Apparatus for locating faults in electric circuits.



no. 689,254. Patented nec. 17, 49m- T. w. v ARLEY. APPARATUS FORLOGATING FAULTS IN ELECTRIC GIRGUITS.

(Application ined Mm. so, 1901.)

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UNITED YSTATES ATENT rrr-ICE.

THOMAS W. VARLEY, OF NEW YORK, N. Y.

APPARATUS FOR LOCATING FAULTS IN ELECTRIC CIRCUITS.

SEECIFICATION forming part of Letters Patent No. 689,254, dated December17, 1901.

Application tiled March 30, 1901. Serial No. 53,586. (No model.)

To all whom it may concern:

Be it known that I, THOMAS W. VARLEY, a citizen of the United States,and a resident of New York, in the county of New York and State of NewYork, have in vented certain new and usefulImprovementsinApparatusforLoeating Faults in Electric Oircuits,of whichthe following is a specification.

My invention relates to an apparatus for locating faults in electriccables carrying elec? tric currents.

The general plan ot the invention is to conncct with the cable formingthe circuit upon which it is desired to locate a fault a supplementalsource of electric currents having such characteristics with referenceto the characteristics of the current normally traversing the cablethatan indicating device moved from point to point along the cable willbe so aected as to indicate the direction from the point of observationat which the fault is present, and thus by successive applicationsthere-- of exactly locate the position of the fault.

The invention is applicable to systems carrying either alternatingcurrents or continuous currents, but for convenience of illustrationwill be described more particularly in connection with analternating-current system. In such system without disconnecting thesource of supply of alternating currents a suitable source of continuouscurrents is connected at one pole with the earth and at the other polewith some convenient portion of the cable or circuit in which a fault isto be located. The continuous current therefore completes its circuit toa greater or less eX- tent through the earth by way of the fault.

A compass or magnetic needle suitably mounted if placed adjacent to thecable carrying continuous current without reference to the alternatingcurrent will be iniiuenced by reason of the continuous current and tendto take a position at right angles to the How of the continuous current,the north-seeking pole of the compass tending to point toward theright-hand side of a cable above which it is placed when the currentflows in a direction from the observer. It will be understood, however,that in the usual construction of underground cables and manholes, moreor less magnetic material being present, the disturbing influences aresuch that the earths attraction is necessarily considerably interferedwith, and some means must be provided for determining the direction ofthe continuous current flowing through the conductor as distinguishedfrom the outside inuences. I therefore usually proyide means for causinga regular determined interruption ofthe flow of the continuous currentand for reasons which will appear cause the cessations in the How ofcurrent to be of a diiferent duration from the continuations thereof.Thus, for instance, the current may be allowed to flow for eight secondsand then interrupted for four seconds. It, therefore, the observernotices that the needle tends to occupy a certain p0- sition for eightseconds and then a different position for th`e succeeding four seconds,it will berapparent. that the position occupied during the eight secondsis the one resulting from the iniuence ot' the flow of current, and byobserving the position of the needle it is possible to determine thedirection of the flow of the direct current, and hence the direction inwhich the fault is located. For convenience a pointer may be carried bythe mag netic needle or compass which b v occupying a position at rightangles-to the length of the compass-needle can be utilized to pointalways in the direction in which to Search for the fault when thecontinuous current is flowing.

It sometimes may chance that the local conditions in a given manhole aresuch that the natural tendency of the needle will be to stand in thesame direction whether the continuous current is flowing or not throughthe cable. Any suitable means-such, for instance, as a supplementalmagnet-may be then ernployed for causing the needle to stand at an angleparallel to the cable when no continuous current is owing therethrough.

In the accompanying drawings, Figure lis a diagram showing a generalorganization of circuits and apparatus for illustating the invention;and Fig. 2. is an enlarged View of a section of cable, showing theindicating devices in connection therewith. trates a modification.

Referring to the drawings, l represents a central station in which islocated any suitable source 2 of electric currents. In this instance itis assumed to be a source of alternating currents. Main-line conductors3 4t 5 Fig. 3 illus- IOO 6 are led from the station in the usual manner,and these are represented as having the primary coils 7 of transformersconnected in parallel therewith. At the point X it is assumed that afault or leak in the main cable has occurred. At the central stationthere is provided any suitable source of continuous current, such asrepresented at 8. One pole of this source is connected with the earth bya conductor 9. The other pole is connected by a conductor 1() through areactive device 11 with one leg--say S-of the main line. The reactivecoil is employed furthe purpose of enabling the connection 0f theconductor 10 to be made with either side of the main circuit, for it isevident that if the connection were made direct from the source ofcontinuous current to the main circuit in such manner that the leak orgrounding of the main circuit were to forni with the grounded side ofthe direct-current source a local circuit for the alternating currentsthen without the protective effects of the reactive coil the apparatusmight be destroyed.

For the purpose of causing successive impulses of definite duration totraverse Ihecircuit 1 employ any suitable form of controllingdevice-such, for instance, as a rotating circuit-closer 12-which in thisinstance is adapted to shunt continuous current from the conductor 10 atdefinite intervals. For this purpose it is provided with successivecontact-plates 13, which pass beneath two contact-arms 111 and l5, whichare connected, respectively, with the opposite poles of the source, andthus when these contact-brushes both rest upon one of thecontact-segments the continuous current will be `shuntedfrom thealternating-current circuit. As already stated, the intervals of openingand closing this shunt-circuit are regulated so that the duration of theone shall be different from that of the other.

An adjustable resistance 25 may be included in the continuous-currentcircuit for the purpose of regulating the strength of the currentpermitted to flow through the main circuit.

, The indicating device is illustrated at 16 and consists of a magneticneedle or bar 17, suitably pivoted and free to revolve in the manner ofa compass-needle. A pointer 18 is shown as being carried by the magneticbar 19, so arranged with respect to the bar that when the latter is in aposition at right angles to the length of the cable by reason of thecontinuous current flowing therethrough the pointer will be directedtoward the fault or leak in the cable. By passing along the cable andplacing the indicating device 16 above the cable at successive manholesthe observer may locate the direction of the fault.

If it be assumed, for instance, that the fault is at the point X, thenthe indicator will point towardI the right hand when placed in theposition shown in full lines in Fig. 1, for instance. If the indicatorbe moved inward to the point indicated in dotted lines, then theindicator will point toward the left hand, and in this manner the exactposition of the fault may be determined. If the iirst observations aretaken at a manhole, including, say, the the points 2O and 21, theindication of the needle would be toward the right hand upon eachconductor 3 and 4, but an indication would be shown upon the conductors5 and 6 in opposite directions, so that the observer would know that thefault was upon the circuit 3 4.

For the purpose of causing the bar 19 to stand in a direction more orless parallel to the length of the cable when the chf-tracteristiecurrent is not iiowing through the line, not even though 'thesurrounding conditions would tend to place it in some differentposition, an adjustable magnet 22 may be employed, and by swinging thisto the proper position the desired initial vposition may be given tothe-bar 19. This magnet may be any suitable form of permanent magnetcapable of being turned upon a pivot central with 'reference to theindicator 18, so as to give to the indicator an initial position inalinement with the cable, so that it will tend to swing when subjectedto the influence of the indicating-currents.

As already stated, the invention is applicable for use on circuits wherecontinuous currents are employed, the general arrangement being the sameas already described with the exception that the indicating deviceinstead of being a compass is, as indicated in Fig. 3, an inductivedevice responsive to the direct currents transmitted from thesupplemental source. Such a device may consist of conductors 23, capableof being placed parallel to the cable or main conductor and havingincluded in their circuit an indicating device 24., responding to theinduced currents setup in the conductor 23, acting as a secondary to themain line. These conductors, placed parallel to the mains, are arrangedso as to neutralize the variations in the working currents, which may bechanging in value and would otherwise interfere with the signals.

The indicating device consists of an instrument that gives a kick orthrow of the needle, as in a ballistic galvanometer 24, and itis the'direction and kick in reference tothe cable,

in connection with the make-and-break apparatus, that determines Athedirection of the fault.

In Fig. 3 I have shown a modified arrangement of apparatusin connectionwith the supplemental generator 8, consisting in the interposition of atransformer or some other device suitable for preventing the currents onthe main circuit from kreaching the supplemental source. For instance,the coil 11 is here made the primary coil of the transformer 29 and hasits terminals connected around resistance 25 and the supplemental source8, while the secondary coil 11a of the transformer IOC) -break or faultin the conductor 4 is indicated at X. The indicating device may beconstructed with two branches 26 and 27, adapted to be placed inparallel relation with reference to the two legs 3 and 4 of the circuitand connected up so that the variations in the normal Working current ofthe line will induce an opposing impulse in the branches with referenceto the indicator 8. Then when a supplemental current is caused totraverse the circuit from the source 8 the portion passing through theconductor 3 and by way of the work-circuit to the point X will at themoment of its increase induce a current in the branch 27 in a givendirection, and the portion passing through the conductor 4 will likewiseinduce in the branch 26 an impulse in the same direction, and the twotogether will cause the galvanometer or indicating device 8 to point foran instant in a given direction, this direction being toward the breakor fault. The indicator will then immediately return to its normalposition; but on the cessation of the supplemental current it will inlike manner receive an impulse in the opposite direction. Inasmuch asthe time intervals between the successive impulses differ from theduration of the successive impulses, it may be readily determined inwhich direction the supplemental current is iiowing, hence whichmovements of the needle are toward the break. It is not always necessarythat this indicating device should be applied to both branches of thecircuit, as the changes in the normal working current may not always besuch as to materially interfere with the reading of the indicationsgiven by the supplemental current.

I claim as my invention- 1. The combination with a system of electricaldistribution, of means for superposing upon the normal working currentsflowing through the conductors thereof electric currents having adifferent characteristic from that of the Working currents of thesystem.

2. The combination with the main source of a system of electricaldistribution, of a su pplemental source of electric current, connectionsfrom one terminal thereof with the earth, connections from the otherterminal thereof with the main circuit, ashunt-circuit around saidsupplemental source, and means for causing a periodic opening andclosing of the said shunt-circuit.

3. The combination with an electric circuit carrying working electriccurrents, of a source of testing-currents, and means for causingdetermined periods of the testing-currents to be su perposed upon theworking current traversingthe circuit, and connections from one end ofthe source of testing-currents With the earth, whereby a ground upon themain cir'- cuit will alord a return-path for the testingcurrents inconnection with the grounded terminal of said source.

e. The combination with a main supply-cir- -cuit of a system ofelectrical distribution, of

a source of continuous currents', connections from one pole of saidsource to the earth, connections from the other pole with some portionof the main circuit, and means for causing electric currents of deiiniteduration to be su perposed upon the working current traversing the maincircuit from said source of continuous currents.

5. The combination with a main supply-circuit of a system of electricaldistribution', of a source of continuous currents, connections from onepole of said source to the earth, connections from the other pole withsome portion of the main circuit, means for causing electric impulses ofdefinite duration to traverse the main circuit from said source ofcontinuous currents, and a reactive coil connected between the maincircuit and said source ot' continuous current.

6. The combination with a main supply-circuit of a system of electricaldistribution, of a source of continuous currents, connections from onepole of said source to the earth, connections from the other pole withsome portion of the main circuit, means for causing electric currents ofdelinite duration to traverse the main circuit from-said source ofcontinuous currents, a reactive coil connected between the main circuitand said source of continuous currents, and an adjustable yresistance inthe continuous-current circuit.

Signed at New York, in the county of New York and State of New York,this 12th day of March, A. D. 1901.

THOMAS W. vARLEY.

Witnesses:

WM. H. OAPEL, EDWARD J. DoLAN.

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